Win or lose in November, Democratic Lt. Gov. John Walsh will be the next senator from Montana.

Gov. Steve Bullock appointed his former running mate to fill the seat of retiring Democratic Sen. Max Baucus, who is leaving the Senate early after being confirmed Thursday as ambassador to China.

Walsh was already running for the seat, but he'll now run as the incumbent senator. That change could provide some inherent advantages in his quest to hold one of the party's most vulnerable seats.

"I wanted to appoint someone who I truly believed would wake up each and every day wanting to put Montana and Montanans first,” Bullock said in a Friday news conference to announce the appointment. National Democrats recruited Walsh to run after former Gov. Brian Schweitzer took a pass on the race. The open seat is a top target of national Republicans, who landed a top-tier candidate in Rep. Steve Daines. Two other Democrats, former Lt. Gov. John Bohlinger and rancher Dirk Adams, are also seeking the nomination.

Walsh said he would fly to Washington, D.C., on Monday and be sworn in on Tuesday.

Running as a sitting senator could offer Walsh considerable fundraising assistance, as he'll be close to Capitol Hill donors and he'll now introduce himself as a senator. The designation also could get more voters to pay attention to the race, while also providing him free media.

Still, those new advantages don't necessarily portend victory in November. Daines, a freshman congressman, raised more than $1 million in the fourth quarter and ended 2013 with $1.9 million in cash on hand. He also launched his first TV ad this week.

Democrats hope to replicate the success of Sen. Jon Tester, who won in 2012 despite a double-digit loss in Montana by President Barack Obama. Walsh even has the same haircut.

"John is the kind of guy who may not agree with the party on every single issue, but he has the selflessness and courage to always do what he thinks is right for Montana, and that is exactly the kind of leadership we need here in the US Senate," Bennet said in a statement released moments after the announcement.